How does Meg show, in chapter twenty, that, even though much of the book goes against the tradition of the times, traditional choices are still alright for some?

Jo tries to convince Meg not to marry John Brooke and Meg seems to agree. She feels she is too young to marry and plans to tell John so, but soon finds herself agreeing to marry him, instead. Like traditional women in those times, she opts for the early protection of a husband.